13,592 research outputs found
Management System for Harvest Scheduling: The Case of Horticultural Production in Southeast Spain
horticultural farmer, optimization, planning, mathematical programming, marketing, cooperative, Agribusiness, Crop Production/Industries, Demand and Price Analysis, Farm Management, Land Economics/Use,
Lifetime Measurement of the 8s Level in Francium
We measure the lifetime of the 8s level on a magneto-optically trapped sample
of ^{210}Fr atoms with time-correlated single-photon counting. The 7P_{1/2}
state serves as the resonant intermediate level for two-photon excitation of
the 8s level completed with a 1300 nm laser. Analysis of the fluorescence decay
through the the 7P_{3/2} level gives 53.30 +- 0.44 ns for the 8s level
lifetime.Comment: 4 pages, 4 figure
Job-shop Scheduling Over a Heterogeneous Platform
Real-time scheduling involves determining the allocation of platform resources in such a way tasks can meet their temporal restrictions.
This work focuses on job-shop tasks model in which a task have a finite number of nonpreemptive different instances (jobs) that share a unique hard deadline and their time requirements are known until task arrival.
Non-preemptive scheduling is considered because this characteristic is widely used in industry. Besides job-shop scheduling has direct impacts on the production efficiency and costs of manufacturing systems. So that the development of analysis for tasks with these characteristics is necessary.
The aim of this work is to propose an online scheduling test able to guarantee the execution of a new arriving task, which is generated by human interaction with an embedded system, otherwise to discart it. An extension of the schedulability test proposed by Baruah in 2006 for non-preemptive periodic tasks over an identical platform is presented in this paper. Such extension is applied to non-preemptive tasks that have hard deadlines over a heterogeneous platform. To do that, some virtual changes over both the task set and the platform are effectuated
Mechanisms of Bacterial Extracellular Electron Exchange.
The biochemical mechanisms by which microbes interact with extracellular soluble metal ions and insoluble redox-active minerals have been the focus of intense research over the last three decades. The process presents two challenges to the microorganism; firstly electrons have to be transported at the cell surface, which in Gram negative bacteria presents an additional problem of electron transfer across the ~ 6 nm of the outer membrane. Secondly the electrons must be transferred to or from the terminal electron acceptors or donors. This review covers the known mechanisms that bacteria use to transport electrons across the cell envelope to external electron donors/acceptors. In Gram negative bacteria electron transfer across the outer membrane involves the use of an outer membrane ÎČ-barrel and cytochrome. These can be in the form of a porin-cytochrome protein, such as Cyc2 of Acidothiobacillus ferrioxydans, or a multiprotein porin-cytochrome complex like MtrCAB of Shewanella oneidensis MR-1. For mineral respiring organisms there is the additional challenge of transferring the electrons from the cell to mineral surface. For the strict anaerobe Geobacter sulfurreducens this requires electron transfer through conductive pili to associated cytochrome OmcS that directly reduces Fe(III)oxides, while the facultative anaerobe S. oneidensis MR-1 accomplishes mineral reduction through direct membrane contact, contact through filamentous extentions and soluble flavin shuttles, all of which require the outer membrane cytochromes MtrC and OmcA in addition to secreted flavin
Stairs detection with odometry-aided traversal from a wearable RGB-D camera
Stairs are one of the most common structures present in human-made scenarios, but also one of the most dangerous for those with vision problems. In this work we propose a complete method to detect, locate and parametrise stairs with a wearable RGB-D camera. Our algorithm uses the depth data to determine if the horizontal planes in the scene are valid steps of a staircase judging their dimensions and relative positions. As a result we obtain a scaled model of the staircase with the spatial location and orientation with respect to the subject. The visual odometry is also estimated to continuously recover the current position and orientation of the user while moving. This enhances the system giving the ability to come back to previously detected features and providing location awareness of the user during the climb. Simultaneously, the detection of the staircase during the traversal is used to correct the drift of the visual odometry. A comparison of results of the stair detection with other state-of-the-art algorithms was performed using public dataset. Additional experiments have also been carried out, recording our own natural scenes with a chest-mounted RGB-D camera in indoor scenarios. The algorithm is robust enough to work in real-time and even under partial occlusions of the stair
Microsolvation of heavy halides
The fundamental question of how intermolecular interactions lead to the stabilization of heavy halides (Brâ, Iâ, Atâ) microsolvated with up to six explicit water molecules is addressed here. An exhaustive exploration of the potential energy surfaces using a random search algorithm followed by optimization of molecular geometries using pseudopotentials and at the full four component relativistic levels of theory, affords a good number of structures with high probabilities of occurrence, highlighting the important role of local minima to reproduce experimentally measured properties. Sequential hydration enthalpies for astatide are reported here for the first time in the scientific literature. Closed shell (ionic, long range) as well as intermediate character interactions (contributions from closed shell and covalent) are at play stabilizing the clusters. The ability of water molecules to either donate or to accept electron density dictates the nature and strength of the corresponding hydrogen bonds in solvation shells. Binding energies and molecular geometries are shown to be more sensitive to electron correlation than to relativistic effects
A common rule for decision-making in animal collectives across species
A diversity of decision-making systems has been observed in animal
collectives. In some species, choices depend on the differences of the numbers
of animals that have chosen each of the available options, while in other
species on the relative differences (a behavior known as Weber's law) or follow
more complex rules. We here show that this diversity of decision systems
corresponds to a single rule of decision-making in collectives. We first
obtained a decision rule based on Bayesian estimation that uses the information
provided by the behaviors of the other individuals to improve the estimation of
the structure of the world. We then tested this rule in decision experiments
using zebrafish (Danio rerio), and in existing rich datasets of argentine ants
(Linepithema humile) and sticklebacks (Gasterosteus aculeatus), showing that a
unified model across species can quantitatively explain the diversity of
decision systems. Further, these results show that the different counting
systems used by animals, including humans, can emerge from the common principle
of using social information to make good decisions
Anisotropic spin-orbit induced splitting of intersubband spin plasmons
The anisotropic splitting of intersubband spin plasmons, resulting from spin-orbit coupling, is studied by angle-resolved inelastic light scattering on a [001]-oriented GaAs/AlGaAs quantum well. Confirming theoretical predictions made in [C. A. Ullrich and M. A. Flatte, Phys. Rev. B ÂŽ 68, 235310 (2003)], this splitting is proven to exhibit a characteristic two-fold symmetry with the in-plane orientation, and to increase with increasing modulus of the excitation momentum. This opens the way to a more complete investigation, aiming at evidencing the existence of a collective spin-orbit field driving these excitations.Fil: Baboux, F.. Universite de Paris Vi. Institut Des Nanosciences de Paris; Francia. Centre National de la Recherche Scientifique; FranciaFil: Perez, F. Universite de Paris Vi. Institut Des Nanosciences de Paris; Francia. Centre National de la Recherche Scientifique; FranciaFil: Ullrich, C. A. . University Of Missouri; Estados UnidosFil: D'Amico, I. . University Of York; Reino UnidoFil: Gomez, Javier Enrique. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Centre National de la Recherche Scientifique; Francia. Universite de Paris Vi. Institut Des Nanosciences de Paris; FranciaFil: Bernard, M.. Universite de Paris Vi. Institut Des Nanosciences de Paris; Franci
Photodiodes based in La0.7Sr0.3MnO3/single layer MoS2 hybrid vertical heterostructures
The fabrication of artificial materials by stacking of individual
two-dimensional (2D) materials is amongst one of the most promising research
avenues in the field of 2D materials. Moreover, this strategy to fabricate new
man-made materials can be further extended by fabricating hybrid stacks between
2D materials and other functional materials with different dimensionality
making the potential number of combinations almost infinite. Among all these
possible combinations, mixing 2D materials with transition metal oxides can
result especially useful because of the large amount of interesting physical
phenomena displayed separately by these two material families. We present a
hybrid device based on the stacking of a single layer MoS2 onto a lanthanum
strontium manganite (La0.7Sr0.3MnO3) thin film, creating an atomically thin
device. It shows a rectifying electrical transport with a ratio of 103, and a
photovoltaic effect with Voc up to 0.4 V. The photodiode behaviour arises as a
consequence of the different doping character of these two materials. This
result paves the way towards combining the efforts of these two large materials
science communities.Comment: 1 table, 4 figures (+9 supp. info. figures
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